Control instrument



April 2, 1929. Y R, p, BROWN 1,707,652

CONTROL INSTRUMENT Filed 00t 29, 1924 2 Sheets-She et l a j, I

r 3 .5 filo L P 9 r R. P. BROWN 1,707,652

CONTROL INSTRUMENT Filed 001;..29, 1924 2 Sheets-:Sheet' 2 INVENTOR Few/men Pfieonav MUZIgJ ATTORNEY Patented Apr. 2, 1929.

- UNITED STATES PATENT OFFICE.

normal) 2. BRowN, or PHILADELPHIA, PENNSYLVANIA, AssIGNoB 'ro THE ImowN INSTRUMENT COMPANY, or PHILADELPHIA, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA.

The general object of my present invention is to provide an improved control instrument of the type in which the actuation of one or more ele tric switches by a tilting depressor or other intermittently operating power actuator is made dependent on the position of the movable element of a galvanometer or other meter. In instruments of the type referred to, the control switch or 10 switches are commonly employed for one or more of the following purposes; to wit, the operation of signals, the adjustment of re-' sistances and marker elements of potentiometer and analogous indicator recorders, and the regulation of the supply of heat to a furnace in response to temperature variations therein to which the meter is responsive. As heretofore ordinarily constructed 1 the meter pointer in an instrument of, the type referred to has served as a means through which the depressor or other power actuator has transmitted to the controlled switch, the energy required for actuating the latter. In accordance with the present invention, the controlled switch is directly engaged and actuated by the depressor or other power actuator in a certain position or range of positions .of the movable element of the control meter, while the latter in another position or range of positions prevents the movement of the power actuator into operative engagement with the last mentioned switch. As a result of this difference the present invention possesses certain im ortant practical advantages as will appear rom the following description.

The invention may be employed in an instrument in which the only control switch is the switch directly-engaged by the-depressor or power actuator as above described, but in a preferred embodiment of theinvention the instrument comprises one or more additional swltches which are actuated 1n the.

pointer in certain predetermined posit-ions of i the pointer. In-such an instrument the additional switch or switches serve as, or as a part of, the means through which the inst-rument pointer prevents the power actuator from operatively engaging the switch directly actuated by said actuator,-escept when CQNTROL INSTRUMENT.

Application filed October 29, 1924. Serial No. 746,710.

the movable element of the meter is in the position or range of positions in which the last mentloned switch should be actuated.

. An instrument of the kind just described is especially well adapted for controlling the supply of heat to a. furnace in response to the furnace temperature. In such usethe switch directly actuated by the depressor may serveto turn on or increase the supply of heat when actuated, and a depressor arresting switch may serve to interrupt or decrease the supply of heat when actuated. In consequence the position of the last mentioned switch determines the maximum temperature normally obtained in the furnace, and by adjusting the position of that switch, the max-- imum furnace temperature may be varied as conditions make desirable, while the range of positions of the instrument pointer in which the heat increasing switch is directly actuated by the depressor, will include the entire range of movement of the pointer at the low temperature side of the temperature limiti' ing switch regardless of the adjustment of the latter. In consequence the instrument may automatically control the operation of the furnace in starting from the cold condition as well as to maintain a close regulation of the furnace temperature in regular oper- .ation.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification; but

for a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and de scriptive matter in which I have illustrated Fig.2 is a somewhat diagrammatic plan view of a portion of the apparatus shown in Fig. .1;

Fig. 3 is a diagrammatic view with parts of the instrument shown in elevation;

Fig. 4 is a view generally similar to Fig. 2 illustrating a modified construction;

.Fig. 5 is a section on the line 5-5 of Fig. 4; i

v apparatus of Figs. 6 and 7.

' In the particular embodiment of the invention shown in Figs. 1, 2 and 3 of the drawings, A represents a galvanometer or milli-volt meter -mounted in a case a and comprising 'a movable element carrying a pointer A swinging about the suspension axis of said element in accordance with variations in the quantity measured by the meter. This quantity in the case of a pyrometer may well be the E. M. F. of a thermo-couple, or the difference between that E. M. F. section of a thermo-couple and the potential drop in a pyrometer resistance section or other balancing circuit. a represents the instrument scale along which the free end of the pointer A moves.

Amociated with the meter proper is a pointer depressor B shown as pivotally connected to the frame workat the meter B and intermittently actuated in a known manner, as by means of a member B and a motor H, to'alternately lift the arc-shaped body b of the depressor above the path of movement of the free end of the pointer A, and then to ermit the body portion 6 to descend und eir the action of gravity and thereby depress the end of the pointer A.and through its projection A. actuate one or another of the control switches as hereinafter explained.

In accordance with. the present invention a control switch G is mounted on the meter frame work out of the normal path of move-- ment of the pointer A, but in position to be engaged and to have its normally separated contacts g brought together, by the depressor B in the final portion of each full down swing of the latter. The depressor B is prevented by the pointer A from swinging down far enough to operatively engage the switch G, when the pointenA is above an abutment or stop located beneath a portion of the path along which the pointer swings. As shown, this abutment or stop is in the form of a table C supported by an arm C which is angularly adjustable about the axis of the movable element of the meter. A' pointer C carried by the arm C indicates on the scale a the setting or adjustment of the table C.

In the instrument shown in Figs. 1, 2, and 3, the table C supports a switch E comprising normally separated contacts e'which are brought together by the instrument pointer A whenever the latter is above the switch E at the instant the depressor B moves downward into engagement with the pointer and thereby forces the latter against the switch E. As shown, the table C also supports a switch F similar to and alongside the switch E, and similarly actuated to bring its normally separated contacts f together when the pointer A is above the switch F at the instant at which the pointer is engaged and depressed by the depressor B.

As already explained, the control switches E, F, and G are capable of use in various ways and for various purposes. In the diagrammatic illustration of one use of the instrument shown by way of example in Fig. 3, the-switches E, F, andG are associated in a control system comprising a pair ofv electro-magnets I and J in such manner that the magnet J will be energized when the switch E is closed and the magnet I will be energized when either of the switches G and F is energized. In this arrangement the closure of the switch E energizes the magnet J from a source of current ;K through circuit connections comprising a conductor 1, switch contacts e, conductor 3, and conductor 2; the closure of the switch F energizes the magnet I through a circuit comprising conductor 1, switch contacts f, conductor 4, and conductor 2; and the closure of the switch G energizes the magnet I through a circuitcomprising conductor 1, contacts 9, conductor 5, and conductor 2.

As diagrammatically illustrated in Fig. 3, i

the magnets I and J operate a control device L which may be, for example, a fuel valve, a heating current control switch, or a relay controller, to increase or diminish the supply of heat to a furnace having a pyrometric control of which the control instrument forms a part, accordingly as the lever connecting the armatures of the magnets I and J is turned in one direction by the energization of the magnet I and in the opposite direction by the energization of the magnet J.

In the instrument shown in Figs. 1, 2, and 3, the switch G serves in effect to extend the range of movement of the pointer A- in which its depression by the depressor B will effect the energization of the magnet I to include all positions of the pointer A at the left or low temperature side of the switch F, without interfering with the adjustment of table C necessary to vary the temperature at which the instrument will cause the switch E to be actuated and there by energize the magnet J. It will be apparent that the omission from the instrument shown in Figs; 1, 2, and 3 of the switch F and the portion of the table beneath that switch would not effect the control of the magnets I and J, but would merely increase the range of positions of the pointer A in which the depressor could operatively engage the switch G. While the switch F may be omitted as shown in Figs. 4-7 and its omission is advantageous from the stand- 7 pointer A were permitted to swing to the right or high temperature side of the abutment formed by the table C, a subsequent downward movement of the depressor B would cause the switch G to be closed under.

a condition in which that switch should remain open. This may be prevented in the apparatus shown in Figs. 1, 2, and 3, by

the provision of a stop C carried by the table C which prevents the pointer A from swinging to the right of thetable C. When the instrument pointer A is thus prevented from swinging to the right of the stop C the pointer can no longer indicate the true value of the quantity measured by the ineter. This ordinarily is not apractically se-' rious defect, for the condition giving rise to a tendency to move the pointer A against the stop C would seldom occur in ordinary 'use as the width of the switch E is ordinarily at least as.g reat,as the range of movement of the pointer beyond the normally neutral position of the pointer which of course is that adjacent the adjacent edges of the switches E and F. In Figs. 4, 5, 6, and

' well as the stop C is omitted, the table C- is provided with an extension C at the high "side of the contact E. In the top of the exhaving a channel 0 .similar in shape and purpose to the channel C of Figs. 4 and 5. The member C is supported at one end by the table C, and adjacent its other end rests a projection A from the instrument frame Work. Advantageously the member (1 is detachably connected to the table C as by means of dowel pins C carried by the table and passing through apertures provided in the member C. This arrangement permits of a considerable range of adjustment in the position of the table G without unduly enlarging the width of the casing necessary to accommodate the portion of the member (1 at the right of the support A over which the member C slides as the table C is adjusted. Further adjustment of the table C may be accommodated by replacing the, member 0 by a longer piece 0 as shown in Fig. 8, or by a shorter piece C as shown in Fig. 9 While in accordance with the provisions of the statutes I have illustrated and described the best forms of my invention now known to me, it will be apparent to those skilled in the art that changes in form may be made without departing from the spirit of my invention as set forth in the appended claims, and that some features of my invention may sometimes be used to ad vantage without a corresponding use of other features.

Having now described my,invention, what I claim as new and desire to secure by Let-- ters Patent, is:

1. In a control instrument, the combination with a meter pointer, of a control device, an intermittently operated actuator adapted on each operation to actuate said device unless prevented from operatively engaging the latter, and .means cooperating with said pointer to prevent the actuator from operatively engaging said device in tension C isan are shaped channel or groovefcertain normal positions of said pointer but the depressor body 6 except when the pointer means.

A is at the low temperature side of'the switch E.

When the contemplated angular adjustmerit of the table C is relatively large and it is undesirable to provide space in the instrument case for a table extension C long enough to accommodate the full range of,

adjustment of the table C, the extension 0 may be supplemented or replaced by other For example, as shown in Figs. 6 and 7, the extension C may be replaced by a part (1 in the form of an arc shaped bar.

inefiective to prevent such engagement in other normal positions of said pointer.

2, In a control instrument the combination with a 'meter'pointer, ot a control device, an intermittently operated actuator adapted on each operation to actuate said device unless prevented from operatively engaging the latter, and means cooperating with said pointer to prevent the actuator from operatively engaging said device in certain normal positions of said pointer but other normal positions of said pointer, said means being adjustable to vary the pointer position in which the said actuator isprevented from operatively engaging said device.

3. In a control instrument, the combination with a meter pointer, of an intermittently operating actuator, a switch operated 'by said actuator through said pointer in one 120 -inefl7ective to prevent such engagement in position of the latter, and a second switch directly operated by said actuator in another position of said pointer.

4. In .a control instrument, the combination with a meter pointer, of an intermittently operating actuator, a switch directly operated by said actuator in certain positions of said pointer, and a second switch operated by said actuator through said pointer in another position of said pointer and then preventing said actuator from operating the first mentioned switch.

5. In a control instrument comprising a swin ing meter pointer, an intermittently tilted depressor, a stop co-acting. with said pointer in certain positions of the latter, to limit the tilting movement of the depressor, and to control device operated by the de pressor when the tilting movement of the epressor exceeds that to which it is limited by said stop in said certain positions of said pointer.

6. In a control instrument, the combination with a meter pointer, of an intermittently operating depressor, a stop adjustable along the path of movement of the needle and co-operating with said pointer to limit the operation of said actuator when said pointer is above said stop and a control device operated by said actuator when said according to the deflection of the pointer,

pointer is not above said stop.

7. In a control system, a meter having a swinging pointer, a switch, disposed along the path of movement of the pointer, an intermittently operating actuator adapted to engage the pointer and thereby actuate'said switch through the pointer in one position of the latter, and a second switch directly actuated b said actuator when said pointer is out of tl ie position for actuating the first mentioned switch.

. 8. In -a control system meter having a swinging pointer, an intermittently operating pointer depressor, a stop adjustable along the path of movement of the needle co-operating with the pointer to limit the depressing movement of the depressor when the pointer is abovethe stop, one or -more control switches carried by the stop and each adapted to be actuated by the depressor and the pointer when the latter is above it, and another switch adapted to be actuated by the depressor on each depressing movement of the latter not arrested by the pointerand the stop.

9. In acontrol instrument, the combination with a meter pointer, of an intermit tentlyoperated actuator, twoswitches selectively controlled by said actuator according to the extent of movement of said actuator, and means dependent on the position mittently operated depressor, of control provisions comprising means dependent on the position of the pointer for limiting the depressing movement of the depressor in one position of the pointer and for permitting a greater depressing movement of the depressor in another position of the pointer and including two control devices one 0 which, is actuated by the depressor when its depressing movement is so limited and the other actuated by the depressor when the greater depressing movement of the latter is permitted. i

- Y 11. In a control instrument, the combination with a meter pointer normally free to deflect in a plane, of an actuator normally at one side 01' said plane, means periodically giving said actuator a movement transversely of said plane into engagement with said pointer,.means dependent upon the deflection of said pointer when en aged by said actuator for selectively limlting the extent of said movement of said actuator circuit controlling means operated by said actuator on the movement of the actuator occurring in one position of the pointer, and

other circuit controlling means operated by said actuator on a movement of the latter greater than that required for the actuation of the first mentioned means.

12. In a control instrument, the combina- 4 mechanism selectively controlled by said ac-.

tuator forexerting one or. another of two opposing efl'ects accordingly as said extent of actuator movement does or does not exceed a predetermined amount."

Signed at Phildelphia, in the county of Philadelphia, and State of Pennsylvania,

this 27th day of October, A. D. 1924.

' RICHARD P. BROWN. 

